1. Field of the Invention
The present invention relates to a data processing apparatus such as a local area network (LAN) connection apparatus used in a full duplex Ethernet LAN system.
2. Description of the Related Art
In a full duplex Ethernet LAN system where a plurality of LAN connection apparatuses (units) are connected by LANs, congestion preventing means is provided in each of the LAN connection units (see: IEEE P802.3X, xe2x80x9cSpecification for 802.3 Full Duplex Operationxe2x80x9d, pp. 100-116, Jun. 4, 1996). That is, when congestion occurs in one LAN connection unit, this LAN connection unit generates a pause packet and transmits it to the other LAN connection units. Then, the other LAN connection units interrupt the transmission of data for a pause time period indicated by the pause packet. As a result, the congestion of the above-mentioned LAN connection unit can be dissolved. This will be explained later in detail.
In the above-described prior art LAN system, however, when one LAN connection unit transmits a pause packet simultaneously to a plurality of other LAN connection units, the transmission of packets is interrupted in the plurality of LAN connection units. In this case, the transmission of packets having destinations to the LAN connection units where congestion does not occur may be interrupted, which retards the entire communication of the LAN system.
It is an object of the present invention to dissolve the congestion state of a data processing apparatus without retarding the entire communication of a data processing system.
According to the present invention, in a data processing apparatus, a receiver receives pause control data signals from other data processing apparatuses. Each of the pause control data signals includes identification data of one of the other data processing apparatuses and a transmission interrupting time period. The identification data associated with the transmission interrupting time period is stored in a memory. Also, when a time corresponding to the transmission interrupting time period has passed, the identification data is removed from the memory. Transmission of data to one of the other data processing apparatuses having the identification data stored in the memory is interrupted.
Thus, the transmission of data only for the data processing apparatus where congestion occurs is interrupted.